New York Mets manager Terry Collins (10) speaks to media...

New York Mets manager Terry Collins (10) speaks to media during Game 5 of the World Series against the Kansas City Royals at Citi Field on Sunday, Nov. 1, 2015. Credit: Newsday/ Thomas A. Ferrara

In the end, what will sting most for these Mets is regret.

As much as this trip to the World Series felt like an unanticipated bonus, a dreamy thrill ride, there's no separating all that accumulated joy from the crushing, painful finality of falling short.

For everything the Mets accomplished this year, losing the last game of the season hurts, no matter how far they came or how unexpected it was. And to twist the knife a bit more, the Mets should still be playing this week in Kansas City.

Three times in this World Series, they were five outs or fewer from a victory, only to have the Royals cruelly snatch it away a handful of innings later. To see that unfold Sunday night at Citi Field was especially harsh, with Matt Harvey's valiant effort evaporating in the ninth and Lucas Duda's desperate, wild throw to the plate unable to prevent Eric Hosmer's daring dash home with the tying run.

The Royals made the whole thing seem academic by blowing up a close contest into a 7-2 final (it took 12 innings) that was as deceiving as the entire World Series itself.

Sure, Kansas City won it in five games, after leading 2-0, but the Mets practically had two of them in their back pocket.

Alex Gordon's gut punch in Game 1, a tying homer off Jeurys Familia with one out in the ninth, that stuff happens. Terry Collins brought his closer in for the five-out save, and he came up two outs short.

In Saturday night's Game 4, the Mets brought a 3-2 lead into the eighth, but Daniel Murphy whiffed on an eighth-inning grounder that should have dulled a Royals rally.

What happened Sunday, however, will gnaw at the Mets much more during this mercifully short offseason.

Matt Harvey had turned in his masterpiece, his Mona Lisa, his "Stairway to Heaven" for eight innings. The Mets had a 2-0 lead, Familia was warm, and all Collins had to do was rubber-stamp this one. But then the chants started: "WE WANT HAR-VEY!"

And with Citi Field calling for its hero, Harvey demanded to go back out for the ninth after throwing 102 pitches. Collins already had made the decision to go with his closer, but he reconsidered after hearing Harvey's plea, allowing the emotion to cloud his judgment.

"I let my heart get in the way of my gut," Collins said. "When you looked in this kid's eyes, when he came off that inning, he's been through a tough summer. He's been beaten down. I just trusted him. I said, 'You got it. You've earned this.' So it's my fault. It's not his. I know better than that."

Collins, who at age 66 is the oldest manager in the majors, has been like a father figure to this group, so to hear him offer that explanation early Monday morning (the game ended at 12:34 a.m.) was hardly surprising. And the only problem we have is sticking with Harvey after the leadoff walk to Lorenzo Cain.

Conventional wisdom dictates that it's time for the closer at that juncture. Collins gave Harvey his shot. That's all a manager owes any of his players. But the ninth inning quickly unraveled from there, with Hosmer doubling home Cain and then pressuring the Mets into making the critical, score-tying mistake with Familia on the mound.

On Salvador Perez's grounder to third, Hosmer practically dared David Wright to chase him down by lunging far off the bag, then bolted for home when Wright threw across the diamond. A merely good throw by Duda would have easily nailed Hosmer. But he made a terrible one.

The previous night, in Game 4, it was Murphy's error that allowed the Royals to score the tying run. Hosmer's chopper skipped beneath his outstretched glove and the energy drained from Citi Field as if someone had pulled the plug.

It was a similar empty feeling Sunday, but with no more opportunities for redemption.

"The Royals won this thing," Wright said. "Obviously, there were some things we could have done differently, but they outplayed us."

Is that really true? Did the Royals come off as that much better? Or were they just the more resourceful, more opportunistic team?

Would bringing in Familia for the start of the ninth have changed the course of this World Series? We'll never know.

The Mets failed to get it back to Kansas City -- despite having numerous chances to do so -- and that's something they'll have to make peace with this winter before they begin their National League pennant defense.

"You can't play the 'what if?' game," Wright said. "That will drive you nuts."

But now that the season is over, it's the only game left. Unfortunately, we already know how that turns out.